When a runner is running at high speed and in particular when he is sprinting, the rolling movement of the foot does not take place in the usual manner from the heel which is first put on the ground. On the contrary, the heel scarcely comes into contact with the ground or does not come into contact with it at all, as the runner first puts the stretched-out foot on to the track in the region of the outside part of the ball of the foot, and it is from there that a rolling movement towards the inside part of the ball of the foot takes place. When the foot is put on to the ground with the outside region of the ball of the foot, that is to say at the first moment of making contact with the ground, the runner first tries to achieve contact with the track, that is to say secure support on the track, in order then immediately to apply leg power to the ground by means of the gripping elements which are fixed to the hard front sole portion of the shoe, during the rolling movement of the foot towards the inward side of the ball of the foot. That first contact with the track in the region of the outside part of the ball of the foot is of essential significance in regard to sure-footed running and in regard to optimum efficiency on the part of the runner, as it is that first contact with the track which substantially determines at least the initial phase of the rolling movement of the foot towards the inside ball region thereof. If the runner does not make contact at the correct location at the outside edge of the sole, then correction of the rolling movement of the foot occurs during such rolling movement, and that correction prevents the immediate and full application of power to the track and consequently represents a drop in efficiency. As long as the runner is fresh, he succeeds in making the first contact with the track in such a way as to provide for an optimum rolling movement of the foot. However, when the runner becomes just slightly fatigued, there is a tendency to make first contact with the track, with regions of the foot which are further towards the rear thereof; finally, when the runner is more seriously fatigued, that tendency results in the heel making first contact with the track. Due to the point at which the foot makes contact with the track being shifted further rearwardly from the outside ball region of the foot however, the tendency to sink back on to the heel in turn becomes more and more pronounced.
There are already many proposals for better controlling the way in which the foot is put on to the track, and the subsequent rolling movement from the outside region to the inside region of the ball of the foot, even when the runner is suffering from a certain amount of fatigue, by virtue of a suitable configuration of running shoes. Thus, running shoes are known in which the hard front sole which carries the gripping elements has a support edge which laterally embraces the upper portion of the shoe in the outer ball region and which blends into the hard front sole with a relatively large rounded configuration (German laid-open application (DE-OS) No 28 05 426). The intention with that design is that the rolling movement from the moment of first making contact with the track until the end of that movement is controlled by that rounded configuration. Admittedly, that shoe construction has proven to be advantageous insofar as, due to the above-mentioned support edge, the runner does not need firstly to try to achieve a secure condition of support on the track in order then to initiate and perform the rolling movement of the foot, but rather the runner can immediately put the foot full on the track and can also already apply leg power to the track, because, when the foot is correctly set down on to the track, the rolling movement automatically takes place over the hard front sole portion with the support edge. However, even that support edge cannot initiate a satisfactory rolling movement if runner fatigue means that the point at which the foot is put on to the track moves further rearwardly in relation to the foot, because the support edge which is also somewhat curved in the longitudinal direction of the sole readily permits the foot to make contact with the track in that way.
It is also already known in relation to a running shoe of the kind set forth in the opening part of this specification, for a cushion of elastic material to be arranged behind the rearmost gripping elements of the front sole, wherein the cushion projects downwardly beyond the front sole (German laid-open application (DE-OS9 No 31 15 488). That cushion is intended to reduce the impact when the foot makes contact with the ground, and it is intended to contribute to the runner keeping contact with the ground in the region of the ball of the foot, and not being able to swing back on to the heel. However that running shoe also does not provide a decisive improvement because the cushion which projects downwardly beyond the front sole necessarily comes into contact with the ground first, more specifically relatively far behind the outside ball region of the foot, so that it interferes with first contact with the track in the outside ball region, which the runner is endeavouring to achieve. As the cushion projects downwardly and is therefore yielding, its capability of controlling the initiation of the rolling movement of the foot from the outside ball region to the inside ball region is only poor. For, because of the flexible nature of the cushion, it leaves the runner considerable scope to try to achieve contact with the track at the correct location on the foot, in dependence on the level of concentration and the strength of the runner.
Finally, a running shoe is also already known in which a heel portion is provided in the form of a heel member consisting of a resiliently yielding material which prevents the foot from tipping back from the front sole to the heel of the foot and which, by virtue of the elasticity of the heel member, is even intended to produce an acceleration component in the direction in which the runner is running (German patent specification No. 2 720 849). As however that heel member is so low that it does not come into contact with the track as long as the runner is in full possession of his strength and is rolling on the forefoot from the outside ball region to the inside ball region, he can basically prevent the point at which the foot first makes contact with the ground moving rearwardly, only when that has already occurred to a certain degree. Then however the foot of the runner has already departed from the stretched condition thereof to such an extent that the desired rolling movement over the ball of the foot and the instantaneous application of power to the ground can only occur, with a time delay.